Just thought I would tell everyone about my experience with adding OEM dual oil coolers to my touring (single oil cooler equipped) FD. I have been monitoring oil temps from my oil pan for the last year or so and have plenty of reasons to improve the oil cooling on my car.

Goals: to maintain OEM fit, finish with USDM front end, while maximizing oil cooling capability and not spending more than $500 for everything. Improve durability of system (by protecting from bent fins). Improve ducting by copious use of DUCT tape

OLD SETUP:
Single stock oil cooler with bad ducting, bent fins, etc. (my old duct was trashed, the plastic piece that's pop riveted to the duct was totally missing, I had to duct tape that part to maintain any kind of "ducting"). Running 10-13 psi boost, stock non-sequential turbos. Ambient temps 60-100*F.

NEW SETUP:
Dual stock oil coolers with new ducting, straightened fins, new gaskets/washers. Coolers and lines were professionally cleaned by OILCOOLERS.COM Duct taped the sh*t out of the plastic ducts, no way in hell air can get around these puppies, they have to go thru them!! Running 10-13 psi boost, stock non-sequential turbos. Ambient temps 60-70*F (look forward to getting more data on hotter days)

BOTTOM LINE: 1st thing I noticed.. my oil pressure was higher than before, by at least 5-10 psi. My old cooler must have been restricting the system somewhat (clogged?). In spirited driving and cruising modes, my oil temps as measured at the pan run about 20-40*F COOLER than before the mod. The temps appear to cool more rapidly as compared to before as well when the car gets moving (ex: would take a few minutes to cool off 10-20*F before now it takes a minute or two). Water seems to run a bit cooler too (about 10*F when in motion). I will be attempting to track the car more in the next year or two at stockish boost levels (10-12 psi)... hope to keep it cool on the track too Sometimes I wonder why Mazda didn't put dualies on EVERY FD.

to get good access to everything. After that, it's a matter of getting the lines in... I went from the pass side, push the lines thru the hole that sits between the radiator shroud and what I think is the front swaybar bracket. You have to be patient with that part... all in all it took me about 4-6 hours just to get the hard lines in and mounted (AFTER I had full access). And another 6-8 to cut up the mesh, bolt up the coolers, install fittings, clips, and then resinstall everything to get the car back on the ground... Other thing is that you need a 23 mm crescent/box end wrench to undo the bajo bolt on the front cover so you can install the new dual o/c line that goes to the pass cooler (you could probably use a big adjustable crescent wrench.. but I couldn't get mine off with it).

Just give me a call. When are you getting deployed? You gonna make the cruise in a couple of days, would love to have you

How much did it cost to have the coolers cleaned? I know that at some point in my car's life it had an engine pop and I would like to reuse the oil cooler...but am afraid of what could be lurking inside. Pacific oil coolers is only 30 minutes away from me...

Those coolers look amazing after they were freshened up.

Also, more restriction in the oiling system will create higher oil pressure. It probably takes more effort to pump the oil through a second cooler. Also, oil pressure gauges aren't that accurate for getting the actual value. Often times they aren't linear or even close to what the gauge is labeled.

How much did it cost to have the coolers cleaned? I know that at some point in my car's life it had an engine pop and I would like to reuse the oil cooler...but am afraid of what could be lurking inside. Pacific oil coolers is only 30 minutes away from me...

Those coolers look amazing after they were freshened up.

They were $150/cooler + $50 to straighten the fins. They also cleaned up my oil lines (three of them: one that goes from oil filter pedestal to driver's cooler, another that goes from front cover to pass cooler, and also the one that goes from cooler to cooler). They did a good job, but their service was less than what I would consider good, and I know there is another place in Texas (AMERICAN COOLER) that does similar work for about the same price. All in all, my grand total was $350 for cleaning my lines and coolers. I have more pics in my gallery. PICS TO CLEANED OIL COOLERS

Quote:

Originally Posted by spanks13

Also, more restriction in the oiling system will create higher oil pressure. It probably takes more effort to pump the oil through a second cooler.

In general, I agree, but since the OP for the OEM gauge is taken from the rear iron, which is DOWNSTREAM of any restriction offered by the oil cooler system, I think it would be less susceptible to an oil pressure increase.

Quote:

Originally Posted by spanks13

Also, oil pressure gauges aren't that accurate for getting the actual value. Often times they aren't linear or even close to what the gauge is labeled.

Also agree, should connect a mechanical gauge to get real readings. I did notice a "trend", however, from before to now, and that is not exactly hard data, but still "noteworthy"

Quote:

Originally Posted by spanks13

Looks like it was well worth it!

I think so, I should have done this long ago. I think every FD driven reasonably hard, ESP IN HOT WEATHER, should have two oil coolers.

Is there an 'ideal' temperature for the oil in the FD? It is interesting to see the temperature readings you got, for comparison, years ago in my old Triumph TR7 I routinely saw temps of 280 to 300 degrees (the car had no oil cooler).

congrats on a 5 star thread. dual oil coolers should be on any modded FD. as we know the rotary rejects more heat thru oil than a piston engine and you have shown a material advantage to going w 2 coolers.

you have gained oil pressure because you dropped oil temp. the two are inversly related.

it is a simple matter to straighten the fins on your cooler. should you wish to monitor oil temps i recommend removing the oil level sensor on the driver's side of the oilpan and brazing a bung to it. i love the FJO temp sensor and digital gauge.

Is there an 'ideal' temperature for the oil in the FD? It is interesting to see the temperature readings you got, for comparison, years ago in my old Triumph TR7 I routinely saw temps of 280 to 300 degrees (the car had no oil cooler).

I guess my point is...the cost-to-benefit ratio?

I would say the cost is minimal for the benefits of increased cooling offered by the duals... Ideal oil temp... according to Racing Beat, oil going into the motor (not measured at the pan) should never go over 205*F. That's pretty darn chilly. Here's from their website: RACING BEAT

Oil temperature is critical in rotary engines. Oil temperature entering the engine should never be allowed to exceed 205°F. While many factors affect oil temperature, oil cooler size and location are very important to consider. Roughly one-third of all engine heat rejected via the water and oil cooling systems goes out through the oil cooler. The oil cooler should get about one-third of the total cooling air flow.

Quote:

Originally Posted by howard coleman

Mike,

congrats on a 5 star thread. dual oil coolers should be on any modded FD. as we know the rotary rejects more heat thru oil than a piston engine and you have shown a material advantage to going w 2 coolers.

you have gained oil pressure because you dropped oil temp. the two are inversly related.

it is a simple matter to straighten the fins on your cooler. should you wish to monitor oil temps i recommend removing the oil level sensor on the driver's side of the oilpan and brazing a bung to it. i love the FJO temp sensor and digital gauge.

nice work Mike showing us the temps.

howard

Thanks HC. I was initially planning on adapting the driver's cooler per your ingenious thread, but just got lazy and decided I would just pick up a set of OE duals when I could get the right price You were my inspiration for the wire mesh, BTW, great idea to protect the fins. The first time I got really concerned with oil temperatures was when I was on a track a year or so ago... temps got to 260*F at the pan! Not good. Having that data, how could I not put duals on my car? I think for a 100% street car you could get by fine, but anyone who really pushes really should have the xtra cooling IMO.

Another awesome thread with impeccable timing for my own use
I will be acquiring dual coolers next week to do the same thing. If you don't mind a PM or two if i have a question I would really appreciate it. This will probably be my biggest project on the FD thus far (suspension, Diff brace, twin power etc were all super easy).

Did you do this by yourself by chance? Just curious if two or three ppl would make this an easier project.

Just a little note:
When I did this mod to my Touring, the seller didn't include the oil return hard line, the one that goes from the 2nd cooler back to the engine. I notice that a lot of people selling their R1/2 oil coolers don't have that line included.

Great thread Mike! The stock dual oil coolers are much more capable than most people on here realize I think(ie you see alot of people with street cars with ridiculously huge aftermarket oil coolers... most of the time with no ducting). I know you said you wanted to keep the USDM look, but if you ever need some additional cooling, I've had the 99spec bumper drop temps an additional 10-20F. That'll prob. be overkill for you, but thought I'd put that here just in case.

Good thread. I also added new dual OEM coolers during my rebuild (at a cost *never* to be repeated). During one of my first test-n-tune track days my new wheels rubbed through the plastic fender well liners right behind the oil coolers. My initial reaction was "Huh, that sucks", but then I realized it might help the flow through the coolers even more, so I cleaned up the edges and put mesh in the holes to keep out debris. I don't have any hard evidence that this actually helps, but it sure seems like it should. My local track is in the high desert, so cooling is paramount to my build decisions. Probably not worth trashing your fender liners to see if it helps, but if you still see temps too high...

Another awesome thread with impeccable timing for my own use
I will be acquiring dual coolers next week to do the same thing. If you don't mind a PM or two if i have a question I would really appreciate it. This will probably be my biggest project on the FD thus far (suspension, Diff brace, twin power etc were all super easy).

Did you do this by yourself by chance? Just curious if two or three ppl would make this an easier project.

No prob, just PM me. Yeah, did it alone, but it would have been nice to have one other person help to pull the lines thru the rad shroud/swaybar bracket hole I mentioned earlier, but that's about it. Everything else is pretty much a solo job for the rest of the stuff.

Thank you for posting that. Damian and GooRoo and I think Rich (GoodfellaFD3S) had them do their OEM coolers. Look up a thread by Goodfella called "spent some time in the garage" or something like that.

Quote:

Originally Posted by Natey

Just a little note:
When I did this mod to my Touring, the seller didn't include the oil return hard line, the one that goes from the 2nd cooler back to the engine. I notice that a lot of people selling their R1/2 oil coolers don't have that line included.

Make sure you get that line! It cost over 100 bucks from the dealer.

Absolutely critical part. Most of the setups I see f/s don't include all the stuff you need.

Quote:

Originally Posted by joel_rx7

Nice and timely thread (as this is my next mod)!

That's even better when people provide data.

Yeah, having had the single cooler and looking at temps for the last year+, I am so happy I added the 2nd one. Every degree counts with these motors, and when you can remove 20-40*F with STOCK equipment, I'd say that's pretty good!

Quote:

Originally Posted by S14.3REW

Wow those oil coolers look clean!

Thanks to you. Appreciate the parts, they were in pretty good shape to start.

Quote:

Originally Posted by Double_J

Great thread! Reading this makes me wonder if oil pressure/temperature played a roll in my engine going.

After I had my engine rebuilt in Dec I drove it home. I noticed my stock oil gauge was reading higher than previous. I didn't make the connection that lower oil temps equal more pressure.

Obviously its much cooler outside now than in the summer time! Duh

I have an R1 with dual oil coolers already but now that I've read this thread I will check the ducts, and fins along with getting proper gauges!

Good to hear. I get the feeling a lot of people who drive these cars underestimate how much heat these motors make as compared to a piston engine of comparable power. Keep oil, water, fuel, and air cool and you are golden!

Quote:

Originally Posted by memphisraines82

Great thread Mike! The stock dual oil coolers are much more capable than most people on here realize I think(ie you see alot of people with street cars with ridiculously huge aftermarket oil coolers... most of the time with no ducting). I know you said you wanted to keep the USDM look, but if you ever need some additional cooling, I've had the 99spec bumper drop temps an additional 10-20F. That'll prob. be overkill for you, but thought I'd put that here just in case.

Thanks Brent, I should have clarified: I much prefer the 99+ bumpers, I think they are dead sexy infact Speaking of overkill, only problem for the near term (and foreseeable future I suppose) is that money is a concern... a proper conversion to 99 spec plus all the other crap I would want to do is out of the question. SO, I was set on making my USDM body work do the job. The 99+ ducts are huge, no question they are better for moving more air thru the coolers. Just look at the 93-95 o/c openings compared to the 99+ ones and you'll realize right away... the 93-95 ones are undersized by comparison.

Quote:

Originally Posted by NV02

Good thread. I also added new dual OEM coolers during my rebuild (at a cost *never* to be repeated). During one of my first test-n-tune track days my new wheels rubbed through the plastic fender well liners right behind the oil coolers. My initial reaction was "Huh, that sucks", but then I realized it might help the flow through the coolers even more, so I cleaned up the edges and put mesh in the holes to keep out debris. I don't have any hard evidence that this actually helps, but it sure seems like it should. My local track is in the high desert, so cooling is paramount to my build decisions. Probably not worth trashing your fender liners to see if it helps, but if you still see temps too high...

Dave...

Thanks for posting the pic. Just be careful that the rear of the coolers don't get messed up by debris (sounds like you put something over it). I think you would need something like 3-5 inches behind the cooler of free space to provide good flow thru the fins... but I'm not a fluid mechanics guy. If it makes you feel any better my driver's fender liner has been chewed up since I got the car, just got a new one the other day to replace it. The high desert... where at? You talking about Buttonwillow, etc.?

Quote:

Originally Posted by RX7 RAGE

Wow, good info Mike. I need to get the R magic ducts for the 99 spec bumper now.

Hey Gene! Still haven't seen your new wheels yet! Yeah, ducting does wonders for any of these heat transfer devices that work with a cooling fin type setup (most radiators, intercoolers, oil coolers, etc.). One of these days I will be 99 spec like you Hope to see you and your car soon.

-stock non-sequential turbos
-93 USDM front bumper cover and OEM ducts
-20W-50 dino oil
-OEM FD dual oil coolers dropped my oil temps, in every condition (traffic, street driving, track) by 20-40*F, as opposed to stock single.
-W/ the single cooler, I used to see 260*F on a slower road course, Cal Speedway infield, May 2008 (see pic of track & vid below).
-Top speeds for me were around 100-110 mph.
-On track I was running lower boost than I do on the street (track, stockish level = 10-11 psi; street = 12-14 psi), probably making 250-270 whp on track.
-That was a cool day too, probably 60-70*F.
-When I hit 260*F oil @ the pan, I had to back off almost every other lap.
-Here's a vid of a portion of that day, skip to 1:16, and yes I suck, I'm a regular Joe who loves FD's, not a race car pro video of "part II" that day

The following pics are not quite to scale. But scale is printed on the track maps. Here is a pic of the infield shown in the video above, running clockwise.

-A lot less stress on motor in that configuration, as compared to a recent track day (Memorial Day weekend 2010) which was a lot higher speed/load.
-Was hitting over 130-135 mph on the oval/nascar bank every lap, pretty much topping out my 4th gear on my rotary powered/geared car.
-Oil hit 240*F tops, that was with mostly WOT conditions, same boost level and rest of the car setup was basically the same, AND it was hotter that day, about 80-90*F.
-Limiting factor that day was water temp, on last 5 minutes of 25 minute sessions (tops was approaching 230*F @ water filler neck), NOT oil temp! (opposite of last track day in 2008, where oil kept me cooling down every other lap).
-Car ran great that day. Running counter clock wise. Memorial day weekend, 2010.

Bottom line: if you drive your car ON A TRACK, weather is hot, you NEED dual oil coolers. I think a pure street car, even with high hp, can get by with a OEM single. The FD OEM ones work great, after gathering the data from the track days and also street driving, I'm convinced! Nothing wrong with aftermarket bigger ones either, just make sure you have a thermostat in them

You may recall that I made a thread a couple weeks ago about dual oil cooler setups for a '94 PEP. I think my friend may go for the used OEM route after all (buying a proper R1/R2 setup), just like you did. It seems to have the greatest benefit per dollar with an easy installation.

Could you give some information about the relationship between oil temp and water temp with the single cooler and the dual coolers? In warmer weather, how close do they tend to be under various types of driving? Are oil temps usually exceeding water temps even with the dual coolers?

It's interesting, on my old non turbo FC (which has the same basic cooling system as the FC turbo models) my oil temps NEVER exceeded water temps. This was an original radiator and FC oil cooler with over 150k on them. I remember doing multiple back-to-back runs at Deal's Gap without stopping to cool down. Oil and water temps were both constant at around 100C/212F. Water temps were measured with an aftermarket gauge in thermostat housing and oil temps were measured with a sandwich plate at the oil filter. I haven't even bothered with an oil temp gauge in my turbo car because I suspected/assumed they would rarely exceed the water temp. The FC factory oil cooler (found on all models, turbo and nonturbo) is a gigantic high quality piece:

Too bad there's no way this would easily fit on an FD, as they are pretty much dime-a-dozen to acquire.

Could you give some information about the relationship between oil temp and water temp with the single cooler and the dual coolers? In warmer weather, how close do they tend to be under various types of driving? Are oil temps usually exceeding water temps even with the dual coolers?

^^ That's a good question, something I've been paying close attention to both before and after I had the duals. I'll try to present this as clearly as I can. The overall trends are more important than the numbers themselves:

Regarding the relationship between water/oil temps on my car, this is for ambient temps from 50-100*F. These are my recollections, not electronically logged. Uncertainty in the temperatures is about +/-5 to 10*F:

*example:
-on recent 90*F track day with lots and lots of 4th gear WOT to ~7500 RPM, did not have to take cooldown laps til very end of of 25 minute session due to high water temp
-oil topped out @ 240*F
-laying off throttle cool down oil almost immediately (after maybe 10-20 seconds, almost 10-20*F)
-took about 15 minutes to get water to 220*F, slowly creeping to 230 over next 5 minutes;

-whereas 60-70*F 2008 track day, not so much 4h gear action (short shifting 3rd-4th a little bit)
-oil was hitting 260*F every other lap (more or less)
-laying off throttle not enough to cool down car... had to drive almost full lap to bring oil from 260 down to 220
-water hit 230*F about 15 minutes in and went between 220-230*F during alternating cooldown laps (more or less)

Hope that helps...

Quote:

Originally Posted by arghx

It's interesting, on my old non turbo FC (which has the same basic cooling system as the FC turbo models) my oil temps NEVER exceeded water temps. This was an original radiator and FC oil cooler with over 150k on them. I remember doing multiple back-to-back runs at Deal's Gap without stopping to cool down. Oil and water temps were both constant at around 100C/212F. Water temps were measured with an aftermarket gauge in thermostat housing and oil temps were measured with a sandwich plate at the oil filter. I haven't even bothered with an oil temp gauge in my turbo car because I suspected/assumed they would rarely exceed the water temp. The FC factory oil cooler (found on all models, turbo and nonturbo) is a gigantic high quality piece:

Too bad there's no way this would easily fit on an FD, as they are pretty much dime-a-dozen to acquire.

^^ I've seen pics of that cooler before. Maybe you could fit it in front of the radiator, I have no idea what the dimensions are on that piece but it sure looks huge! Probably wouldn't work on an OEM front bumper I'd reckon.